[TowerTalk] [Bulk] Re: Fwd: Aluminum towers -- can you really "walk one up"?

[Patrick Greenlee]

I understand all the issues you are mentioning.  If the 2x4 makes you 
nervous then 1. don't watch carpenters raise walls with them or Amish 
raise barn walls with them and 2 nail two of them (or 2x6) together at 
right angles to reduce bending.  I understand the simple leverage 
issues.  Hence using the "pole" to push at a higher level than the man's 
height.  If using 2x6 at right angles then stagger the boards and use 
maybe 12 footers to make a 24 ft or longer pole for better leverage.

Patrick   NJ5G

On 3/9/2015 9:07 AM, Grant Saviers wrote:
> nope, as you walk in, more of the weight of the tower is behind you. 
> Another way to think about this is what size torque wrench would you 
> need to raise the tower if it was attached to a hinge bolt? Ans: 
> HUGE.  A 300# 85' tower needs a torque (moment) of 300*42.5= 12,750 
> ft-lbs to move it just up from horizontal. Assuming the sections are 
> uniform, we can use a mass one half the length, so with a tapered 
> tower it will be less.  Or you can weigh each section, and use the 
> distance to eacg section center when assembled and add up the moments 
> for a fairly accurate approximation of the initial raising moment.
>
> Yes, the lifting load at the end is only 1/2 the weight (less for a 
> tapered tower), but as you walk in the force needed increases. At 45 
> degrees a little geometry will show where you will be trying to hold 
> the tower up. Then calculate the load - from the 12,750 ft-lbs of 
> moment (actually not quite accurate since the changing geometry helps 
> a bit).
>
> A 16' 2x4 has very poor buckling strength, perhaps a recipe for disaster.
>
> A walking or fixed derrick is the way to go.
>
> Grant KZ1W
>
> On 3/9/2015 6:29 AM, Patrick Greenlee wrote:
>> Say what?  If the tower were not tapered (lets look at a simple 
>> model) and you picked up the top then you would support 1/2 the 
>> weight and the ground via the hinges would be holding the other half 
>> of the weight. The higher the top of the tower goes the greater the 
>> portion of the weight is held by the ground/hinges until when 
>> vertical the ground holds all the weight.
>>
>> Buy a 16 ft 2x4 and either notch one end and apply duct tape to 
>> secure it to about 16 ft above the tower base or otherwise secure it 
>> with wire or...
>> Then as you lift the tower the 2x4 can take the load while you rest, 
>> change hands, take a break or ... Once the tower is lifted so high 
>> the 2x4 is not securing the tower very well grab hold of the 2x4 and 
>> use it to push on the tower.  The increased leverage pushing at the 
>> 16 ft level rather than at your head height or so will make a 
>> considerably easier time of it.
>>
>> Archimedes said something like given a lever long enough and a place 
>> to stand he could bend the lever (move the Earth) or some such.
>>
>> Patrick    NJ5G
>>
>> On 3/8/2015 11:45 PM, Richard (Rick) Karlquist wrote:
>>> On 3/8/2015 5:36 PM, Hans Hammarquist via TowerTalk wrote:
>>>
>>>> If you don't put to much heavy stuff on the tower before you walk 
>>>> it up it should be OK. Just for your comparison, I have an 85 feet 
>>>> aluminum tower and the total weight of the tower, empty is 300 lb. 
>>>> It's tapered so the heavier section are at the bottom. No, I didn't 
>>>> walk this tower up but I easily carried around the top 40 feet 
>>>> during the assembly of the tower and could, probably have raised 
>>>> the by myself as a 40 foot tower, had I done that.
>>>
>>>> Hans - N2JFS
>>>>
>>>
>>> I made some calculations and determined that the
>>> force you have to apply to a 40 foot tower of
>>> uniform cross section with nothing on top works
>>> out to 1.7 times the weight of the tower.  And
>>> you have to be able to apply this force using
>>> one hand at a time while you "walk".  It all
>>> depends on the weight of the tower and the
>>> strength of the walker.  Can you hold an 85
>>> pound barbell over head and pass it back and
>>> forth between your hands?  Then you can walk
>>> up a 40 foot tower weighing 50 pounds.
>>>
>>> Rick N6RK
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